Consider the following characteristics of a tropical cyclone:

$1$. A warm sea temperature of more than $26°$ $\mathrm{C}$.

$2$. High relative humidity of atmosphere at a height of more than$700 \mathrm{m}$.

$3$. Atmospheric instability.

The above mentioned characteristics are associate with which one of the following cycles of its development?

Who among the following was the Chairman of the interdisciplinary committee constituted by the Government of India to examine a framework for virtual currencies?

The Indian Railways have gone in for qualitative improvements since independence. Which of the following have taken place in recent years?

$1$. Gauge conversion

$2$. Track electrification

$3$. Automatic Signals

Select the correct answer using the codes given below:

Which of the following statement(s) about magnetite ore of iron is/are correct?

$1$. It is known as black ore.

$2$. It contains$60\%$ to $70\%$ of pure iron.

$3$. It possesses magnetic properties.

 Select the correct answer using the codes given below: